For example, in a manufacturing process of semiconductor devices, a photolithography process is performed by a coating and developing system including a plurality of apparatuses such as a resist coating apparatus, a developing apparatus, a heat treating apparatus and the like. The coating and developing system has a transfer mechanism for transferring a wafer to each of the apparatuses.
The transfer mechanism has a transfer arm for holding the wafer thereon, and, for example, the transfer arm moves three-dimensionally in forward-backward, left-right, and up-down directions to transfer the wafer to each apparatus.
However, in case that the wafer is not transferred to a preset position in each apparatus, the delivery of the wafer may not be performed properly or processing of the wafer may not be carried out properly because of a deviation of a processing position of the wafer, for example. For this reason, when starting the coating and developing system, for example, it is checked whether or not the transfer arm has transferred the wafer to the preset position. In the event that the wafer is not transferred to the right position, the transfer point of the transfer arm is adjusted.
Patent Document 1 discloses an example method for adjusting the transfer position, wherein the method involves the steps of holding a trajectory-detecting wafer having a CCD camera by the transfer arm; transferring the trajectory-detecting wafer by the transfer arm; and detecting a transfer stop position of the transfer arm by the CCD camera.
[Patent Document 1] Japanese Patent Laid-open Publication No. 2003-243479
However, an optical apparatus such as the CCD camera needs to have a sufficient thickness in a vertical direction due to the necessity of an adjusting mechanism of a focus, a focal length or the like. For this reason, as for an apparatus having a reduced opening size due to miniaturization of the wafers being transferred, it is impossible to load the trajectory-detecting wafer into the apparatus, and to adjust the position thereof properly, either.
Therefore, the present inventors have proposed mounting a thin electrostatic capacitance sensor on a position detecting wafer instead of the CCD camera. With this position detecting wafer, it is possible to detect an electrostatic capacitance between the position detecting wafer and a reference object and to detect the transfer point of the transfer arm by specifying a relative positional relationship between the reference object and the position detecting wafer based on the detected electrostatic capacitance value. However, when the electrostatic capacitance sensor is used on the position detecting wafer, there is a likelihood that the electrostatic capacitance may not be detected accurately and stably by being affected by, for example, an electric field if a generation source of the electric field is located nearby. In such case, an accurate detection of the transfer point of the transfer arm becomes impossible to achieve.